add desc to whatsnew

Author: tonyyuyiding

doc/source/whatsnew/v3.0.0.rst

@@ -696,6 +696,7 @@ Indexing
 - Bug in :meth:`DataFrame.loc` with inconsistent behavior of loc-set with 2 given indexes to Series (:issue:`59933`)
 - Bug in :meth:`MultiIndex.insert` when a new value inserted to a datetime-like level gets cast to ``NaT`` and fails indexing (:issue:`60388`)
 - Bug in printing :attr:`Index.names` and :attr:`MultiIndex.levels` would not escape single quotes (:issue:`60190`)
+- Bug in :meth:`DataFrame.__setitem__` throwing a ``ValueError`` when setting a column with a 2D object array (:issue:`61026`)
 
 Missing
 ^^^^^^^